Among various image forming devices, such as printers, facsimiles, copiers, multi-function peripherals, and plotters, there is an image forming device which has a liquid discharge device in which a liquid discharging head for discharging a droplet of a recording liquid is provided as a recording head.
For this image forming device, a maintenance/recovery device which is provided to maintain and recover the performance of the recording head which discharges the recording liquid is indispensable. Generally, this maintenance/recovery device comprises a moisture-retaining cap, a suction cap member, a wiper blade, and an idle discharge receptacle.
The moisture-retaining cap member is provided to cover the nozzle surface with high sealing nature being maintained, in order to prevent fixing of the recording liquid near the nozzle due to natural evaporation of the recording liquid as the ink. The suction cap member is provided for attracting and discharging the recording liquid with high viscosity from the nozzle. The suction cap member may be used to concurrently serve as the moisture-retaining cap member. The wiper blade is provided for wiping off and removing the recording liquid adhering to the nozzle surface. The idle discharge receptacle is used when performing idle discharging in which a droplet of the recording liquid which does not contribute to the image formation is discharged.
Generally, the cap member provided for use in the maintenance/recovery device includes a contact member which is made of an elastic member and contacts the nozzle surface of the recording head, and a recess-forming member in which the recess for receiving the recording liquid attracted from the nozzle on the nozzle surface is formed.
Japanese Patent No. 3106783 discloses a cap member for a conventional ink-jet printing device. This cap member includes the first slope that is loosely inclined toward the ink outlet, and the second slope that extends from the first slope and is steeply inclined toward the ink outlet, so that the remaining ink near the ink outlet may be reduced.
Japanese Laid-Open Patent Application No. 2001-071514 discloses a cap member for a conventional ink-jet printing device in which the tapered space part which is continuously reduced toward the ink outlet is formed, and the ink holding means is disposed in the pipe passage connecting the ink suction port to the negative pressure generating means. The ink in the tapered space part is discharged, and the moisture inside the cap member is retained with the ink in the pipe passage.
Japanese Laid-Open Patent Application No. 6-238915 discloses a cap member for a conventional ink-jet printing device in which the water repellent agent is applied to the inside surface of the cap member for increased water repellence. This cap member is directed to facilitating the ink suction of the cap member by reducing the ink adhering to the cap inside surface.
Japanese Laid-Open Patent Application No. 2003-001839 discloses a cap member for a conventional ink-jet printing device, the cap member being comprised of the elastic sealing member covering the nozzle surface, and the rigid member forming the sealed space part. This cap member is directed to raising the air-tightness. Either or both of the elastic sealing member and the rigid member are formed from a water repellent material with the contact angle to the ink being 90 degrees or more.
For the purposes of obtaining good coloring nature and high reliability, the dye ink is initially used as the coloring agent of the ink in the ink-jet recording device as the image forming device. In recent years, however, in order to give light resistance and water resistance to a recorded image, there is the major trend in which the pigment ink which containing a pigment, such as carbon black, is used increasingly.
Moreover, there is also the trend in which the viscosity of the ink is raised for the purposes of making the flexibility of ink prescription high and preventing the blotting of an image on a plain paper after the discharged ink reaches the plain paper.
In the case of the above-mentioned pigment ink with high viscosity, the ink viscosity greatly changes with temperature. Although some difference arises according to the ink prescription, the ink which has a viscosity of 8 cp at 22 degrees C. may have a viscosity exceeding 15 cp at 10 degrees c, and may have a viscosity of about 5 cp at 32 degrees c.
According to the experiments of the inventors of the present invention, when such high-viscosity ink is attracted to the conventional cap member, it is difficult to stably discharge the ink with the conventional cap member used.
In the case of the cap member of Japanese Patent No. 3106783, the remaining ink near the ink outlet may be reduced. However, when the pigment ink, especially the pigment ink with a high viscosity of 5 cp or more, is used, there is the problem in that the discharging of the ink becomes inadequate.
Also, in the case of the cap member of Japanese Laid-Open Patent Application No. 2001-071514, there is the problem in that the discharging of the ink becomes inadequate when the pigment ink, especially the pigment ink with a high viscosity of 5 cp or more, is used.
In the case of the cap member of Japanese Laid-Open Patent Application No. 6-238915, the suction of the ink is facilitated by increasing the water repellence of the cap inside. However, when the pigment ink with a viscosity of 5 cp or more and a surface tension of 40 mN/m or less at 25 degrees C. is used, the ink wettability is extremely high even if the water-repellent finish is given. For this reason, it is confirmed that the discharging of the ink is not enough.
Moreover, when the contact member which contacts the nozzle surface, and the recess-forming member in which this contact member is provided are integrally formed by molding, it is difficult to apply the water repellent agent uniformly to the recess inside the recess-forming member in which the contact member is provided.
Furthermore, in the case of the cap member of Japanese Laid-Open Patent Application No. 2003-001839, it is confirmed that, when the pigment ink with the viscosity of 5 cp or more and the surface tension of 40 itiN/m or less at 25 degrees C. is used, it is difficult to form either or both of the elastic sealing member and the rigid member from a water repellent material with the contact angle to the ink being 90 degrees or more.